The instant invention is directed to polyols derived from 4,4,4-trichloro-1,2-epoxybutane and/or epihalohydrin which are especially suited for use in preparing foams which may be heat sealed, for example dielectrically. The polyol is formed by alkoxylating an initiator, then reacting the product with 4,4,4-trichloro-1,2-epoxybutane (hereafter referred to as "TCBO") and/or an epihalohydrin, and subsequently capping with a second alkylene oxide.
U.S. Pat. No. 3,244,754 discloses a process wherein a halogen-containing epoxide, which includes TCBO, is reacted with a monomeric polyhydric alcohol in the presence of a Lewis acid. Ethylene glycol and glycerol appear to be the preferred polyhydric alcohols. A divisional of this disclosure, U.S. Pat. No. 3,269,961, is directed to the use of these polyols in the production of polyurethane foams. U.S. Pat. Nos. 3,850,856; 3,219,634; 2,599,799; or 3,081,354 disclose the preparation of polyols by polymerizing an epihalohydrin in the presence of ethylene glycol or other polyoxyalkylene glycols.
U.S. Pat. No. 3,402,169 discloses a process for preparing polyhalogenous polyhydroxy ethers. In one embodiment an initiating compound may be reacted sequentially with two alkylene oxides (column 3, lines 35-38), forming a "block" type polymer. The preferred embodiment, however, appears to be a random mixture of polyhalogenous and nonhalogenous alkylene oxides. The preferred initiating compound is trimethylolpropane, although condensates of alkylene oxides with polyhydric alcohols are disclosed (column 6, lines 11-14). The preferred first alkylene oxide is 1,1,1-trichloro-2,3-epoxy-propane, although TCBO is used in Example 54. The preferred second alkylene oxide is propylene oxide. U.S. Pat. Nos. 3,102,893 (Example 2) and 3,258,495 (Examples 6, 9 and 17) disclose reacting an alcohol with an epoxyalkane and subsequently with epichlorohydrin. U.S. Pat. Nos. 3,415,902 and 3,576,906 disclose epihalohydrin polymers prepared by simultaneously reacting a polyfunctional initiator, epihalohydrin, and an alkylene oxide, preferably propylene oxide.
U.S. Pat. No. 3,741,921 discloses a process for preparing a polyurethane foam wherein the polyol component is the reaction product of TCBO and a sucrose-based or dextrose-based material. The sucrose-based or dextrose-based material includes an oxyalkylated mixture of dextrose or sucrose, and water and/or a polyhydric alcohol. In Example 7 propylene oxide and TCBO are simultaneously added to an alkoxylated initiator. Since the propylene oxide is more reactive than TCBO, the end groups are predominantly TCBO.
U.S. Pat. No. 3,847,844 suggests reacting alkylene oxide with polyhydroxy initiator, before, concurrently with, or after the addition of TCBO (column 4, lines 3-9).
TCBO is used in the polyols of the cited references as a flame retardant. The references discussed do not disclose the use of TCBO or an epihalohydrin in preparing foams which may be dielectrically heat sealed.
It is often commercially desirable to emboss foams, binding a portion of the foam to itself, or to bond foams to substrates. One example is in binding furniture foam cushions or automobile seat foams to upholstery covers. This has traditionally been accomplished by stitching the material to the foam. However, this method is time consuming and expensive. Heat sealing, for example dielectric heat sealing (rotational friction heating induced by radio frequency), provides an economical and faster process of binding the foam and substrate. U.S. Pat. Nos. 3,674,718 and 4,060,439 disclose heat sealable polyurethane foams. The prior art methods used a polyvinylchloride dispersion or cyanoethyl groups to provide polar groups for rotational friction heating. The solids in the dispersions tended to settle or migrate causing irregular sealing characteristics. The use of cyanoethyl groups in the mixtures often resulted in degradation of the polymer before the dielectric heat sealing temperature was reached. The disadvantages of these prior art foams are substantially overcome by using the polyols of the instant invention.
It was found that polyols prepared according to the sequential reactions of initiator+TCBO, initiator+AO+TCBO, initiator+epihalohydrin or initiator+AO+epihalohydrin lacked the necessary reactivity of the terminal alcohol groups to produce foams with good processibility or acceptable compression set. It was further found that polyols prepared according to the sequential reactions of initiator+TCBO+AO or initiator+epihalohydrin+AO led to foams which either had extremely low melt strengths and/or unacceptable compression sets. It was surprisingly found that the block polyols of the instant invention produced foams with excellent melt strength (heat sealability), processing latitude and compression set.